A heat sink is a term for a component or assembly that transfers heat generated within a solid material to a fluid medium, such as air or a liquid. Examples of heat sinks are the heat exchangers used in refrigeration and air conditioning systems and the radiator (also a heat exchanger) in a car. Heat sinks also help to cool electronic and optoelectronic devices, such as higher-power lasers and light emitting diodes (LEDs).
A heat sink is physically designed to increase the surface area in contact with the cooling fluid surrounding it, such as the air. Approach air velocity, choice of material, fin (or other protrusion) design and surface treatment are some of the design factors which influence the thermal resistance, i.e. thermal performance, of a heat sink. One engineering application of heat sinks is in the thermal management of electronics, often computer central processing unit (CPU) or graphics processors. For these, heat sink attachment methods and thermal interface materials also influence the eventual junction or die temperature of the processor(s). T
The rate at which heat is transferred from a heat sink, q, is the product of the heat transfer coefficient (h), the heat transfer surface area (A) through which heat is transferred and the temperature gradient (ΔT).q=h·A·ΔT where
q=heat flow in input or lost heat flow, J/s=W
h=heat transfer coefficient, W/(m2K)
A=heat transfer surface area, m2 
ΔT=difference in temperature between the solid surface and surrounding fluid area, K
The heat transfer coefficient has SI units in watts per meter squared-Kelvin: W/(m2K).
As the heat transferred from a heat sink is proportional to the heat transfer surface area, the higher is the heat transfer surface area of a heat sink, the higher would be the heat transferred from the heat sink.
The most common heat sink material is aluminum. Chemically pure aluminum is not used in the manufacture of heat sinks, but rather aluminum alloys. Aluminum alloy 1050A has one of the higher thermal conductivity values at 229 W/m·K. However, it is not recommended for machining, since it is a relatively soft material. Aluminum alloys 6061 and 6063 are the more commonly used aluminum alloys, with thermal conductivity values of 166 and 201 W/m·K, respectively.
Copper is also used since it has around twice the conductivity of aluminum, but is three times as heavy as aluminum. Copper could be around four to six times more expensive than aluminum. Aluminum has the added advantage that it is able to be extruded, while copper can not. Copper heat sinks are machined and skived. Another method of manufacture is to solder the fins into the heat sink base.
However, none of the conventional heat sink materials have a superplastic forming characteristic that would allow them to be thermoformed by processes such as stamping to create extremely high heat transfer surface area at a micro- and nano-level.